High-bandwidth Digital Content Protection (HDCP™) is utilized for digital content protection, providing for encryption of content or data transmitted over digital interfaces, such as High-Definition Multimedia Interface (HDMI™), which is a compact audio/video interface for transmitting uncompressed digital data. In today's HDCP protocol, all types of content or data (e.g., audio data, video data, control data, etc.) of data streams is encrypted when communicated between a transmitting system and a receiving system. Therefore, none of the content of an encrypted data stream can be used until that content is decrypted at a downstream HDCP receiver (e.g., high-definition television (HDTV)). In case of Mobile High-Definition Link (MHL™), a bridge chip can be employed to serve as an intermediate receiving device and facilitate communication and transmission of MHL-based data streams between mobile devices (e.g., cell phones) and HDMI receivers. MHL is distinguished from HDMI in that MHL refers to a mobile audio/video interface standard for connecting mobile devices (e.g., smart phones) to other devices (e.g., HDTV). Neither HDMI nor MHL requires or defines encryption and HDCP is one of many encryption processes that can be employed for encryption purposes.
Since, using existing HDCP protocol, all types of content in HDMI and MHL data streams are fully encrypted, even in a case where it would be beneficial to amend or at least view certain content of the stream (such as control content for formatting reasons), the entire data stream is required to be transmitted to the end receiving device where it has to be completely decrypted before it can be accessed and analyzed.
It is contemplated that various signaling protocols (e.g., Original Encryption Status Signaling (OESS), Enhanced Encryption Status Signaling (EESS)) may be used between transmitters and receivers for providing and detecting encrypted data streams, such as whether encryption of a data stream is enabled or disabled. For example, EESS protocol is used with the HDMI protocol (and is an optional feature in the Digital Visual Interface (DVI™) protocol), while OESS is used with the DVI protocol.